Michelle Obama clearly hasn't lost that youthful look! Today the former First Lady took to Instagram and shared a throwback photo from her high school prom. "Throwing it back to my 1982 prom night and this pink satin, polka-dotted dress," Obama said of the retro photo.

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Michelle Obama's prom throwback has an important purpose

While she looks as radiant as ever today, Obama didn't post the picture for vanity reasons. She included a caption encouraging students and educators to share their own prom photos using the hashtag #PromChallenge... for a political cause! 

"If you're a student or teacher," Obama said in her post, "join the #PromChallenge with @whenweallvote and @MTV and tell us what your school is doing to register students to vote -- you could get a free prom for your school!"

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See Michelle Obama's high school prom photo here!

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